1. Field of the Invention
This invention relates to apparatus for generating seismic signals useful for geophysical mapping and exploration. The invention is particularly directed towards improvements in a low energy seismic signal generating device as revealed in the above-referenced Application Ser. No. 963,982, which is in the form of a base which supports a projectile firing gun. A seismic energy signal is generated in the earth when a projectile fired from the gun impacts in the earth's surface. The present invention is an improvement in this basic concept including the use of a spatter plate and diaphragm extending across the lower end of the base to keep the base free of impacted dirt and to contain and quiet the muzzle blast.
2. Description of the Prior Art
As is stated in more detail in Application Ser. No. 963,982, seismic energy signals for exploration purposes may be generated in a variety of ways, including the use of explosives, vibrating devices, and so forth. A unique improvement in the generation of seismic signals is introduced in the referenced patent application which describes an apparatus for firing a projectile into the earth's surface. The projectile firing seismic signal generating device has several advantages over previously known techniques, including economy, ease of movement from one place to another, reduced crew requirements, minimum space requirements, minimum disruption of the environment, and so forth.
The present invention is directed towards an improvement in the projectile fired seismic energy generating device by providing a means of intercepting objects, liquid and gas which are displaced from the surface of the earth as the projectile is fired into it. An advantage of the invention to be described is that it assists in muffling the sound of firing projectiles.
It is therefore an object of this invention to provide improvements in a portable low energy seismic source.
More particularly, an object of this invention is to provide an improvement in the transportable type of low energy seismic generating device employing a projectile firing gun mounted on a base, by providing means with the base for intercepting solid objects, liquids and gases which are displaced when a projectile is fired into the earth to prevent such material from being compacted against the interior of the base and to assist in muffling the sound of firing a projectile for seismic purposes.
Another object of this invention is to provide an improved base for a projectile firing gun for use in generating seismic signals, the base including an internal spatter plate and improved means of safely venting the gas as a projectile is fired.
These general objects as well as other and more specific objects will be fulfilled in the following description and claims, taken in conjunction with the attached drawings.